Filtering Issue in a Parameterized Lookup

We've recently implemented a parameterized lookup in our development environment (v13.3) that will allow for selection of certain codes (a custom attribute, we call them cost centers - a dynamic list of instances of a custom cost center object) based upon a selection made in another custom attribute, which we call a funding source (a static list.) The logic displays correctly and, whenever we select a value, it is stored properly. To this end, the lookup works correctly.

However, sometimes the result set of cost centers can be somewhat large, so it would be helpful to filter within the lookup by either the name or the code. When we enter a value and try to filter the results, nothing happens. A loading icon is shown, but the result set isn't filtered; it's as if the end user entered in nothing! Additionally, we've found that the predictive text in the field entry (not in the lookup browse pop-up window) does not work either. Unfortunately, our clients will not accept this from us.

I'd like to ask you all if this is something you've experienced before and, if you have experienced it, please chime in with what you've done to resolve it or if it's a known bug.

Note: We're planning an upgrade in the near future, so we have a sandbox environment for v14.3. Unfortunately, this issue continued to present itself in there as well.